This squeeze generally is of more serious concern among unions with 50,000 or fewer members. Most of these lack the strong financial reserves on which the biggest unions can count. Many find their resources insufficient to serve members.

At the same time, large unions are seeing their old membership strongholds dwindling, particularly in manufacturing fields. They now are looking outside their historical jurisdictions for growth. Not only are they eyeing the fast-growing service industries, but they also are courting small unions covering other occupations.

This is leading to some odd new partnerships.

The United Steelworkers of America, many of whose 1.2 million members have been laid off or discharged from closed mills, and the 20,000-member Insurance Workers International Union (IWIU) are considering a merger. Such a merger would protect the IWIU and would give the steelworkers union a toehold from which to expand into the largely unorganized insurance and financial services field.

The Service Employees International Union (SEIU) recently absorbed the small Jewelry Workers, a merger that joins a struggling 10,000-member union with an SEIU that claims 625,000 members in this country. The SEIU also is negotiating with the Retail, Wholesale &amp; Department Store Union for a merger that would create a much broader-based union in AFL-CIO with more than 800,000 members.

The United Food &amp; Commercial Workers (UFCW), itself established last year by a merger, is about to conclude an agreement that would add the 35,000-member Barbers &amp; Beauticians International Association to its ranks. The UFCW is interested in more than a million barbers and beauticians, who are without union representation in the US and Canada. It also is trying to move into the banking field.

The United Automobile Workers (UAW) last year took in the independent District 65, Distributive Workers of America, representing 35,000 members in office and technical jobs at universities, publishers, and retail stores.

The UAW, the steelworkers, the International Brotherhood of Teamsters, and others all have expressed an interest in expanding white-collar or office and professional organizing.

The American Federation of Teachers (AFT), once dealing exclusively with education, has gone into the health-care field and already has organized some 20 ,000 nurses. There's still talk, but no action, in the AFT and National Education Association about an eventual merger that would create the country's largest and perhaps most powerful labor organization.